In the medical field, an optical imaging device configured to image information inside an object, such as a living body, acquired upon irradiation of the object with light from a light source, such as a laser, has been intensively studied.
One of such optical imaging techniques is photoacoustic imaging (PAI). In the photoacoustic imaging, an acoustic wave detector (e.g., a probe) detects a photoacoustic wave (which is typically an ultrasonic wave) generated upon irradiation of an object with pulsed light which is emitted from a light source. By analyzing the detection signal mathematically, it is possible to obtain optical property value distribution within the object. The optical property value distribution may include initial acoustic pressure distribution, optical energy absorption density distribution and absorption coefficient distribution. Such information may be used for a quantitative measurement of a special material in the object, such as oxygen saturation in the blood.
Recently, pre-clinical studies to image blood vessel figures of small animals using the photoacoustic imaging and clinical studies to apply this principle to, for example, diagnosis of the breast cancer have been intensively continued (“Photoacoustic imaging in biomedicine” M. Xu, L. V. Wang, REVIEW OF SCIENTIFIC INSTRUMENT, 77, 041101, 2006).
However, in the optical property value distribution obtained by the photoacoustic imaging, decreases in resolution and in quantitativity have occurred due to various factors. Therefore, in the photoacoustic imaging, further improvement in resolution and in quantitativity has been needed.